From aa8f73c890f19d8492a7f8aa1a7537440280da9f Mon Sep 17 00:00:00 2001
From: PatR <rankin@nethack.org>
Date: Thu, 15 Sep 2022 14:14:12 -0700
Subject: [PATCH] empty horn of plenty

Format a horn of plenty whose charge count is unknown but is known to
be empty as "empty horn of plenty" like is done for real containers.

This was too easy; I must have missed something....
---
 include/obj.h | 16 ++++++++++++++--
 src/mkobj.c   |  8 +++++++-
 src/objnam.c  | 10 ++++++----
 3 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/include/obj.h b/include/obj.h
index 52f922887..84fe5befc 100644
--- a/include/obj.h
+++ b/include/obj.h
@@ -121,10 +121,22 @@ struct obj {
     Bitfield(in_use, 1); /* for magic items before useup items */
     Bitfield(bypass, 1); /* mark this as an object to be skipped by bhito() */
     Bitfield(cknown, 1); /* for containers (including statues): the contents
-                          * are known; also applicable to tins */
-    Bitfield(lknown, 1); /* locked/unlocked status is known */
+                          * are known; also applicable to tins; also applies
+                          * to horn of plenty but only for empty/non-empty */
+    Bitfield(lknown, 1); /* locked/unlocked status is known; assigned for bags
+                          * and for horn of plenty (when tipping) even though
+                          * they have no locks */
     Bitfield(pickup_prev, 1); /* was picked up previously */
+#if 0
     /* 3 free bits */
+#else
+    /* not implemented */
+    Bitfield(tknown, 1); /* trap status known for chests */
+    Bitfield(eknown, 1); /* effect known for wands zapped or rings worn when
+                          * not seen yet after being picked up while blind
+                          * [maybe for remaining stack of used potion too] */
+    /* 1 free bit */
+#endif
 
     int corpsenm;         /* type of corpse is mons[corpsenm] */
 #define leashmon corpsenm /* gets m_id of attached pet */
diff --git a/src/mkobj.c b/src/mkobj.c
index 18ac0fe7e..7de478aee 100644
--- a/src/mkobj.c
+++ b/src/mkobj.c
@@ -2556,6 +2556,10 @@ hornoplenty(
         impossible("bad horn o' plenty");
     } else if (horn->spe < 1) {
         pline1(nothing_happens);
+        if (!horn->cknown) {
+            horn->cknown = 1;
+            update_inventory();
+        }
     } else {
         struct obj *obj;
         const char *what;
@@ -2604,8 +2608,10 @@ hornoplenty(
             targetbox->owt = weight(targetbox);
             /* item still in magic horn was weightless; when it's now in
                a carried container, hero's encumbrance could change */
-            if (carried(targetbox))
+            if (carried(targetbox)) {
                 (void) encumber_msg();
+                update_inventory(); /* for contents count or wizweight */
+            }
         } else {
             /* assumes this is taking place at hero's location */
             if (!can_reach_floor(TRUE)) {
diff --git a/src/objnam.c b/src/objnam.c
index af873e9be..165b7b07d 100644
--- a/src/objnam.c
+++ b/src/objnam.c
@@ -1144,10 +1144,12 @@ doname_base(
            (when that is known, suffix of "(n:0)" will be appended,
            making the prefix be redundant; note that 'known' flag
            isn't set when emptiness gets discovered because then
-           charging magic would yield known number of new charges) */
-        && ((obj->otyp == BAG_OF_TRICKS)
-             ? (obj->spe == 0 && !obj->known)
-             /* not bag of tricks: empty if container which has no contents */
+           charging magic would yield known number of new charges);
+           horn of plenty isn't a container but is close enough */
+        && ((obj->otyp == BAG_OF_TRICKS || obj->otyp == HORN_OF_PLENTY)
+             ? (obj->spe == 0 && !known)
+             /* not a bag of tricks or horn of plenty: it's empty if
+                it is a container that has no contents */
              : ((Is_container(obj) || obj->otyp == STATUE)
                 && !Has_contents(obj))))
         Strcat(prefix, "empty ");